In the nine-month study of about 475 patients, dalcetrapib raised HDL levels by 31% compared with placebo. It did so without increasing blood pressure or impeding blood flow through the blood vessels.

The findings should ease safety concerns about HDL-boosting drugs that were raised when dalcetrapib's predecessor, torcetrapib, was shown to increase blood pressure and raise the risk of heart attacks and death from heart disease.

"We saw no toxic effects [with dalcetrapib]," says study leader Thomas Luescher, MD, of University Hospital Zurich in Switzerland. "I think we can say it is safe and has no untoward effects and it does the job as far as the [HDL cholesterol] profile is concerned."

Still, researchers won't know how effectively dalcetrapib fights heart disease until results of a late-stage study now enrolling thousands of patients are in -- and that won't be for at least two years, Luescher tells WebMD. Also, it is not yet clear whether raising levels of good cholesterol will prevent heart attacks and strokes, says Keith Fox, MD, of the University of Edinburgh, who put the findings into perspective for attendees at the European Society of Cardiology Congress 2011.

Plus, more patients have to be followed for longer periods of time to ensure the drug is safe over the long term, he tells WebMD.

A second, 130-patient study presented at the meeting showed dalcetrapib was well tolerated and slowed the progression of atherosclerosis, or fat build-up in blood vessel walls.

Long-Term Data Needed

Like its predecessor torcetrapib, dalcetrapib inhibits a protein called CETP that is responsible for transforming good cholesterol into bad cholesterol. But it blocks a different part of the protein.

A third CETP blocker called anacetrapib that targets yet another part of the protein is also in testing.

The new study involved patients with, or at high risk for, coronary artery disease. They were given either dalcetrapib or placebo daily for nine months.